The invention is related to structural bonded joints that are frangible due to impact momentum that is moderated during displacement by elastic tension means and further related to structural members able to survive impact by energy absorption despite displacement to new secure telescoping structural bonded surfaces and are thus restabilized. And further related to structures of polymer matrix composites impacted by low-velocity, non-ballistic impacts communicated by structural, hydraulic or pneumatic means.
The invention is also directed to pipe sections constructed and their structural connections, and more particularly to couplings between bonded telescoping members providing static support where an impacted member thrusts a conical taper, flare, or bulge into a more static member to sequentially stretch a multitude of circumferential wound bands, fiber tows, hybrid tow, wire, braid, or polymer-impregnated high-modulus fiber strips to retard the momentum of the impacted member whereby structural stability is maintained after impact. They represent a class of devices that support structural load, yield to impact, and regain structural support and re-stabilization.
In the structural field, impacts on columns, frames, and trusses are generated by moving vehicles at velocities under 70 mph. A vehicle running over a brick lying on a bridge deck sends a jolt into the entire supporting truss structure. If the structure is constructed of composites it may only weigh a fraction of the equivalent weight of a reinforced concrete structure. This smaller mass drastically increases impact vulnerability. Composites members are also weaker in compression than tension.
Aerospace structures may experience low-velocity impact. Space station trusses are at risk during docking. Landers risk engine failure, or an unsuitable site. In space, structural deformity is acceptable if collapse is prevented.
Hydraulic or pneumatic shock absorbers are common, but not for long-term structural loads since their seals would fail. A device is needed to absorb applied fluidic impact by structural means exterior of reservoir integrity.
In the prior art it is common to find impact absorption that occurs orthogonal to the direction by bending. An automobile leaf spring is an example.
In the prior art it is common to find single-impact-use absorbers. Bumpers, crumple zones, and steering columns of an automobile are examples. Damage to these components is justified to prevent or moderate human injury.
In the prior art of fiber energy absorption, deformation and breakage predominates because ballistic damage has been a focus. For high-velocity impacts the affected fiber length is short being measured in multiples of fiber diameter. Low-velocity impacts have time to access a more substantial fiber length. The available length of a continuous fiber wound around a 7.6 inch pipe would be 24 inches. This 24 inch fiber would have about 1000 times the low-velocity energy absorption capacity compared to simple fiber breakage.